This application claims priority under 35 USC 119 from Japanese Patent Application Nos. 2002-167635 and 2002-329095, the disclosure of which is incorporated by reference herein.
1. Field of the Invention
The present invention relates to a pattern forming method and a pattern forming device for forming a wiring pattern or a circuit of a wiring substrate.
2. Description of the Related Art
In conventional wiring pattern forming methods, a three-dimensional wiring pattern (a solid wiring pattern) is formed by repeating the processes of dielectric film formation, photolithography, and plating.
In such methods, a highly-accurate mask aligning technique is required at each layer, and a drawback arises in that the processes become longer. Further, there is the need to manufacture an expensive mask each time the wiring pattern of the wiring substrate changes, and a drawback arises in that costs increase.
In the photolithographic process, the following method (spin coating) is employed: a wiring substrate, on which large droplets of a photosensitive polymer solution have been applied, is rotated at high speed around an axis. The photosensitive polymer solution is thereby discharged toward the outer side, and the wiring substrate is coated by a thin film of the photosensitive polymer solution.
However, when the wiring substrate is rotated at high speed, almost all of the photosensitive polymer solution scatters without coating the surface, which is a waste of the photosensitive polymer solution.
Moreover, it is easy for dust to adhere to the surface of the wiring substrate. When a liquid organic substance is applied on the surface of the wiring substrate, protrusions form due to the adhered dust, and regions shaded by these protrusions are formed behind the protrusions. Thus, relatively thin, radially-shaped traces of the organic substance remain at the rear sides of these protrusions, and pattern defects arise.
In view of the aforementioned, an object of the present invention is to provide a wiring pattern forming method and a wiring pattern forming device which can flexibly handle changes in wiring patterns without the need for a mask. Another object of the present invention is to provide a wiring pattern forming method and a wiring pattern forming device which are relatively strong with respect to dust and defects existing on a substrate, and in which there is no waste of solution during the coating processes.
A first aspect of the present invention provides a pattern forming method which comprises the steps of: forming a pattern by discharging droplets of a conductive material forming solution onto an insulating substrate; forming a conductive layer pattern on the pattern by discharging droplets of a solution which becomes a growth core; and forming a metal pattern by immersing the conductive layer pattern in a plating liquid.
In the first aspect of the present invention, because a pattern is formed by discharging droplets of a conductive material forming solution onto an insulating substrate, there is no need for a mask. Further, a thin film can be formed by dispersing the conductive material forming solution in water. Thus, a fine pattern can be formed.
In the first aspect, the droplets of the insulating material forming solution, the droplets of the conductive material forming solution, and the droplets of the solution which becomes a growth core are discharged perpendicularly to the insulating substrate.
Due to the droplets of the respective solutions being discharged perpendicularly to the insulating substrate, the wiring pattern is not affected by dust or defects existing at the insulating substrate, and pattern defects do not arise.
Droplets of the solution which becomes a growth core are discharged onto the pattern which is formed as described above. In this way, a conductive layer pattern is formed. The conductive layer pattern is immersed in a plating liquid, and a metal pattern is formed. Note that the metal pattern may be formed by using copper as the copper plating. A pattern which has high electrical conductivity can thereby be obtained. Moreover, the pattern may be dried and rinsed before the droplets of the solution which becomes a growth core are discharged.
Moreover, the pattern forming method further comprises the step of forming a protective layer on a surface of the metal pattern by discharging droplets of an insulating material forming solution except at regions which are to become electrodes of the metal pattern.
A protective layer is formed on the surface of the metal pattern by discharging droplets of an insulating material forming solution except at regions which are to become electrodes of the metal pattern. This protective layer may be formed as needed (on demand).
Here, xe2x80x9cpatternxe2x80x9d encompasses wiring patterns and circuits. By changing the thickness or the configuration of the pattern, a resistor, a capacitor, or the like can be formed.
Further, a metal pattern is formed three-dimensionally on the insulating substrate by repeating the respective steps plural times.
By repeating plural times the discharging of the droplets, a metal pattern can be formed three-dimensionally without positioning masks many times.
Moreover, the droplets of the insulating material forming solution, the droplets of the conductive material forming solution, and the droplets of the solution which becomes a growth core are discharged from ink jet heads in accordance with a layout of the patterns and the protective layer.
The pattern can be easily changed by controlling the positions of discharging, merely by inputting pattern information of the pattern to the control device which controls the ink jet heads. Thus, the process for manufacturing a wiring substrate or a circuit can be shortened.
A second aspect of the present invention provides a pattern forming method which comprises the steps of: forming a pattern groove on an insulating substrate by discharging droplets of an insulating material forming solution; discharging droplets of a conductive material forming solution into the pattern groove; forming a conductive layer pattern by discharging droplets of a solution which becomes a growth core, onto a pattern formed by the conductive material forming solution, and forming a metal pattern by immersing the conductive layer pattern in a plating liquid.
A pattern groove is formed on an insulating substrate by discharging droplets of an insulating material forming solution. A pattern can be formed by discharging droplets of a conductive material forming solution into the groove portion of the pattern groove so as to fill the groove.
Namely, by forming a metal pattern in the groove formed by the insulating material forming solution, short circuiting between metal patterns can reliably be prevented.
A third aspect of the present invention provides a pattern forming device which comprises: an insulating solution ink jet head discharging an insulating material forming solution; a conductive solution ink jet head discharging a conductive material forming solution; a growth core solution ink jet head discharging a solution which becomes a growth core; a heating mechanism heating an insulating substrate set on a base; a head scanning mechanism which causes the insulating solution ink jet head, the conductive solution ink jet head, and the growth core solution ink jet head to scan above the base; a control mechanism which, on the basis of inputted layout information of a wiring pattern and a protective layer protecting the wiring pattern, operates the scanning mechanism and makes droplets be discharged from nozzles of the insulating solution ink jet head, the conductive solution ink jet head, and the growth core solution ink jet head; a base raising/lowering mechanism which raises and lowers the base; and a moving mechanism at which a rinsing tank and a plating tank are disposed, and which moves one of the rinsing tank and the plating tank to beneath the base as needed.
All of the processes for forming the pattern on the insulating substrate are carried out in a state in which the insulating substrate is positioned on the base. Thus, there is no need to position the insulating substrate for each process, and a highly accurate pattern can be formed.
In the third aspect of the present invention, the insulating solution ink jet head, the conductive solution ink jet head, and the growth core solution ink jet head are disposed in lines.
Moreover, the insulating solution ink jet head, the conductive solution ink jet head, and the growth core solution ink jet head are movable only in a direction substantially perpendicular to a direction in which the insulating solution ink jet head, the conductive solution ink jet head, and the growth core solution ink jet head are disposed in lines.
By disposing the ink jet heads in lines along the transverse direction of the insulating substrate, a pattern can be formed at one time by scanning in one direction.
Moreover, the conductive solution ink jet head and the growth core solution ink jet head are thermal-type ink jet heads.
The insulating material forming solution may be a solution in which a heat-resistant resin is dissolved in a solvent. Further, the droplets of the conductive material forming solution and the solution which becomes a growth core may be discharged from thermal-type ink jet heads, and the droplets of the insulating material forming solution may be discharged from a piezoelectric-type ink jet head.
In addition, the insulating solution ink jet head, the conductive solution ink jet head, and the growth core solution ink jet head are each provided with a plurality of nozzles which discharge droplets.
A plurality of discharging nozzles of the ink jet head can be formed in a line along the transverse direction of the insulating substrate, and droplets can be discharged from the respective discharging nozzles in accordance with the layout of the pattern and the protective layer.